CN106283101B - A kind of preparation method of ultra-pure hydrogen - Google Patents

Abstract

The invention discloses a method for preparing ultra-pure hydrogen. The invention adopts an electrolytic hydrogen production process, pretreats the demineralized water before electrolysis, heats the demineralized water, and dissolves all kinds of gases such as N ₂ and Ar in it. Removal, feeding high-purity oxygen to maintain pressure, and then through catalyst catalytic deoxidation and molecular sieve dehydration process, filtration and dust removal process, steel cylinder drying treatment process, to produce ultra- pure hydrogen. The beneficial effects of the present invention: successfully avoid the high cost and small production capacity of the palladium alloy diffusion membrane (tube) separation method, the short service life of the hydride and the unstable production in the hydrogen storage alloy absorption and release method, and the need to use liquid nitrogen in the low temperature adsorption method The disadvantage of high equipment requirements is that it has the characteristics of low production energy consumption, high process efficiency, simple process and stable production.

Description

A kind of preparation method of ultrapure hydrogen

technical field

The invention relates to a method for preparing hydrogen, in particular to a method for preparing ultra-pure hydrogen.

Background technique

With the development of science and technology, the quality and technical requirements for hydrogen are getting higher and higher, and ultra-pure hydrogen with a purity of 99.9999% is required. Ultra-pure hydrogen has a wide range of applications. It is an important raw material for modern electronics, optical fibers, petrochemicals, and some cutting-edge technologies; It is an indispensable source of high-purity gas for the development and production of semiconductor integrated circuits and optical fibers, integrated optics and nano research, crystal epitaxial growth, etc. , rocket fuel analysis and other fields to carry out an important guarantee for the work.

At present, there are three production methods at home and abroad, namely:

1. Palladium alloy diffusion membrane (tube) separation method. Using pure hydrogen as raw material, its membrane (tube) only allows hydrogen and its isotopes to pass through, so as to obtain ultra-pure hydrogen. The film (tube) of this method is extremely expensive, the production cost is extremely high, and the production volume is extremely small.

2. Hydrogen storage alloy absorption and release method. Under a certain temperature and pressure, metals such as titanium series, zirconium series, and rare earth series can absorb a large amount of hydrogen gas, and the hydrogen gas absorbed and stored per unit volume can be 1000 times that of the gaseous state at the same temperature and pressure. High-pressure, high-quality, ultra-pure hydrogen with two major components. Because the hydride itself is very unstable in this method, it is easily poisoned by harmful components. If it is used repeatedly for a long time, the performance will obviously decline. At the same time, there is still a problem of mechanical strength. The current hydrogen storage alloy material is repeatedly absorbed and released, and it needs to be replaced after a few applications, which is costly.

3. Low temperature adsorption method. This method generally produces hydrogen by electrolysis of water. First, high-purity hydrogen is produced by catalytic adsorption process, and then high-pressure high-purity hydrogen is adsorbed at low temperature at the evaporation temperature of liquid nitrogen to remove trace impurities such as nitrogen, oxygen, carbon monoxide, carbon dioxide, methane, and water. Obtain ultra-pure hydrogen. The production of ultra-pure hydrogen by this method requires high energy consumption and high equipment requirements. In addition, there are still problems in temperature control and liquid nitrogen adjustment in the actual operation process, which makes the device unable to produce normally and the product quality is very unstable.

In view of the shortcomings of the above three ultra-pure hydrogen production methods, some new ultra-pure hydrogen preparation methods have been reported, and there are more than one method. CN 101691209 A Provides a high-pressure high-purity hydrogen as raw material, which is screened and developed by the School of Chemistry of Peking University. It has a large adsorption capacity for nitrogen and oxygen (especially for nitrogen), and can remove other trace impurities at the same time, which is different from general 4A, 5A, 13X, etc. The adsorbent is a new type of pu-8 adsorbent, and adopts a new technology of 10 times excessive adsorbent dosage, 6 times lower common adsorption gas velocity, self-controlled purification of impurities under high pressure, and direct tank filling of clean ultra-pure hydrogen cylinders, successfully producing ultra- A new approach to pure hydrogen. CN 105268282 A discloses a method for preparing ultra-pure hydrogen by low-temperature pressure swing adsorption. The method uses 99.999% high-purity hydrogen purified by electrolysis of water as raw material, cools it down to -30~35°C, and then enters the four-tower pressure swing The pressure swing adsorption system of the adsorption method realizes the industrialization of the four-tower cycle. These inventions have been innovated on the basis of the original technology, and can produce ultra-pure hydrogen that meets the national standard, but there are still problems of complicated process, large investment and high cost.

Contents of the invention

In view of the problems existing in the above method for preparing ultra-pure hydrogen, the present invention adopts the electrolytic hydrogen production process to pretreat the softened water before electrolysis, introduce high-purity oxygen to maintain pressure, and then use catalytic deoxidation and molecular sieve dehydration processes to filter and remove dust. Drying treatment process, the purity of ultra-pure hydrogen produced meets the requirements of "GBT 3634.2-2011 pure hydrogen, high-purity hydrogen and ultra-pure hydrogen", and has the characteristics of high output of ultra-pure hydrogen, low investment and stable production.

The technical scheme that the present invention solves its technical problem to take is:

A method for preparing ultra-pure hydrogen, comprising the following steps:

(1) Preheating: Preheat the softened water in the softened water tank;

(2) Pressure maintenance: Introduce high-purity oxygen into the demineralized water tank preheated in step (1) to maintain pressure;

(3) Electrolysis: Cool the softened water in step (2) and pass it into the water electrolysis system for electrolysis to produce electrolytic hydrogen;

(4) Catalytic deoxygenation: the electrolytic hydrogen produced in step (3) is passed through a deoxygenation catalytic tower to remove impurities such as oxygen;

(5) Dehydration and drying: the electrolytic hydrogen after removal of impurities in step (4) is cooled by a cooler, and then free water is removed by a steam-water separator, pressurized, and after the pressurization, it passes through a high-pressure steam-water separator and enters a molecular sieve tower to remove water and carbon dioxide .

(6) Filtration and dust removal: In step (5), the dehydrated and dried electrolytic hydrogen is filtered through a filter to remove impurities to obtain ultra-pure hydrogen.

In the step (1), the preheating temperature is preferably 95~100°C. Within this temperature range, the solubility of Ar, N ₂ , CO, CO ₂ , CH ₄ and Cl ₂ in water is almost zero (see Table 1, Table 2), the preferred preheating time is 10~30min, to remove all Ar, N ₂ , CO, CO ₂ , CH ₄ and Cl ₂ dissolved in it.

In the step (2), the preheated demineralized water is filled with high-purity oxygen to maintain the pressure. The pressure is preferably 0.02-0.04 MPa, and the temperature is lowered while maintaining the pressure. The cooling temperature is preferably 0-40°C. Due to the pressure-holding effect of high-purity oxygen, Ar, N ₂ , CO, CO ₂ , CH ₄ and Cl ₂ in the air are prevented from being dissolved in demineralized water again.

The deoxygenation catalytic tower is used in the step (4), which can reduce the energy consumption of the catalytic deoxygenation reaction. As an optimization, the catalyst used in the deoxygenation catalytic tower is the catalyst HC-1 developed by the Dalian Institute of Chemical Physics, Chinese Academy of Sciences. The deoxidation The working temperature of the catalytic tower is preferably 50±20°C, and impurities such as oxygen in the electrolytic hydrogen can be further removed through this step.

In the step (5), equipment such as a steam-water separator, a high-pressure steam-water separator, and molecular sieves are used to fully remove impurities such as moisture and carbon dioxide in the electrolytic hydrogen. As an optimization, the electrolytic hydrogen is pressurized to 15MPa, and the molecular sieve is preferably 13XAPG molecular sieve , consisting of two groups, one for use during work and one for regeneration.

The step (6) further removes mechanical impurities from the dehydrated and dried electrolytic hydrogen, so that the purity of hydrogen is further improved. The ultra-pure hydrogen obtained through step (6) is compressed before filling the bottle. Carry out special drying treatment on steel cylinders to remove dust and water in the cylinders, and then fill them after pumping to a vacuum.

Table 1 Solubility of gases in water

Table 2 Argon (Ar) absorption coefficient

Note: The absorption coefficient refers to the gas volume absorbed by 1 volume of water when the gas partial pressure is equal to 101.325KPa.

The beneficial effects of the present invention are: the present invention has developed a novel method for preparing ultra-pure hydrogen that is simple to operate and effective, and successfully avoids the high cost of the palladium alloy diffusion membrane (tube) separation method and the high cost of the hydrogen storage alloy absorption and release method. The disadvantages of hydride are short service life, low-temperature adsorption method needs to use liquid nitrogen and the process is unstable. When preheating the demineralized water, various difficult-to-remove impurities such as N ₂ , Ar, CH ₄ are removed, and ultra-pure hydrogen can be obtained after electrolysis, which is different from other methods in which high-purity hydrogen is generated by electrolysis first, and then The process route of purifying high-purity hydrogen has the characteristics of low production energy consumption, high process efficiency, simple process and low cost.

Detailed ways

The preferred embodiments of the present invention are described in detail below, and the experimental methods not indicating specific conditions in the preferred embodiments are carried out according to conventional conditions.

The information of the main equipment used in the following examples is: 2m ³ demineralized water tank, which is equipped with heating coil and condensing device; water electrolysis hydrogen production device: model: ZDQ-125/1.5, hydrogen rated output: 125Nm ³ /h; catalytic deoxidation tower, the catalytic deoxidation tower uses two sets of electric heating devices to ensure the reaction temperature: Dryer: including steam-water separator, high-pressure steam-water separator and molecular sieve tower, of which there are two groups of molecular sieve towers. One group works and another group regenerates. The aforementioned equipment not marked with a specific model is an industrial conventional equipment purchased from the market.

Example 1

Through the above-mentioned production equipment, the preparation of high-purity oxygen is carried out according to the following process:

(1) Preheating: Heat the softened water in a 2m ³ softened water tank to 100°C under normal pressure for 15 minutes, and dissolve all Ar, N ₂ , CO, CO ₂ , CH ₄ and Cl ₂ in the water remove;

(2) Pressure maintenance: Introduce high-purity oxygen into the demineralized water tank preheated in step (1) to maintain pressure. The pressure is 0.3MPa. The pressure-holding effect of oxygen prevents Ar, N ₂ , CO, CO ₂ , CH ₄ and Cl ₂ in the air from being dissolved in demineralized water again.

(3) Electrolysis: The demineralized water cooled to 30°C in step (2) is passed into the water electrolysis hydrogen production device for electrolysis to produce electrolytic hydrogen. After testing, there are impurities such as water and carbon dioxide in it.

(4) Catalytic deoxygenation: The electrolytic hydrogen produced in step (3) is introduced into the deoxygenation catalytic tower for deoxidation. At a temperature of 50±20°C, the catalyst HC-1 developed by the Dalian Institute of Chemical Physics, Chinese Academy of Sciences is used for catalysis, so that The impurity oxygen in the electrolytic hydrogen reacts with hydrogen to generate water, and the electrolytic hydrogen containing 99.999% hydrogen is obtained.

(5) Dehydration and drying: the electrolytic hydrogen after the impurity removal in step (4) is cooled by a cooler, and then free water is removed by a steam-water separator, then pressurized to 15MPa, passes through a high-pressure steam-water separator, and then enters a molecular sieve tower to remove water and For carbon dioxide, the molecular sieve is preferably 13XAPG molecular sieve, which consists of two groups, one group is used during work, and the other group is regenerated.

(6) Filtration and dust removal: The dehydrated and dried electrolytic oxygen in step (5) is filtered through a filter to remove mechanical impurities to obtain ultra-pure hydrogen with a purity of 99.99995%. See Table 3 for details of its indicators.

Before compression and bottle filling, the steel cylinder containing ultra-pure hydrogen is specially dried to remove dust and water in the bottle, and then filled after being pumped to a vacuum to produce bottled ultra-pure hydrogen.

Table 3 Example test results

The above-mentioned specific embodiments are only specific cases of the present invention. The scope of patent protection of the present invention includes but is not limited to the product form and style of the above-mentioned specific embodiments, any method for preparing ultra-pure hydrogen that meets the claims of the present invention and any Appropriate changes or modifications made by those skilled in the art shall fall within the scope of patent protection of the present invention.

Claims (5)

1. a kind of preparation method of ultra-pure hydrogen, which is characterized in that include the following steps：

（1）Preheating：Softened water in water softener tank is heated to 95 ~ 100 DEG C, preheating time is 10 ~ 30min；

（2）Pressurize：To step（1）It is passed through high purity oxygen gas pressurize in water softener tank after preheating, dwell pressure is 0.02 ~ 0.04MPa cools down in pressurize, and cooling temperature is controlled at 0 ~ 40 DEG C；

（3）Electrolysis：By step（2）In softened water be passed through water electrolysis system after cooling and be electrolysed, output electrolysis hydrogen；

（4）Catalytic deoxidation：By step（3）The electrolysis hydrogen of middle output passes through deoxidation catalytic tower imurity-removal oxygen；

（5）Dehydration and drying：By step（4）Dissociate except the electrolysis hydrogen after impurity is removed after cooler cools down with steam-water separator Water, electrolysis hydrogen are pressurized to 15MPa, and by high-pressure stream-water separator after supercharging, moisture and carbon dioxide are removed into molecular sieve tower；

（6）Dust removal by filtration：Step（5）The electrolysis hydrogen of dehydration and drying is filtered, and removes impurity to get ultra-pure hydrogen.

2. a kind of preparation method of ultra-pure hydrogen according to claim 1, it is characterised in that：The step（4）Deoxidation is catalyzed Tower used catalyst is the catalyst HC-1 that Dalian Inst of Chemicophysics, Chinese Academy of Sciences develops.

3. a kind of preparation method of ultra-pure hydrogen according to claim 1, it is characterised in that：The step（4）Deoxidation is catalyzed Tower operating temperature is controlled at 30 ~ 70 DEG C.

4. a kind of preparation method of ultra-pure hydrogen according to claim 1, it is characterised in that：The step（5）Molecular sieve is 13XAPG molecular sieves.

5. a kind of preparation method of ultra-pure hydrogen according to claim 1, it is characterised in that：The step（6）What is obtained is super Pure hydrogen carries out drying and processing before bottle is filled in compression, to steel cylinder, removes dust and water in bottle, vacuum pumping loading.